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Date: Wed, 29 Mar 2017 14:08:02 -0700 From: Mike Kravetz <mike.kravetz@...cle.com> To: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org Cc: Dmitry Vyukov <dvyukov@...gle.com>, Hillf Danton <hillf.zj@...baba-inc.com>, Michal Hocko <mhocko@...e.com>, "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, Andrey Ryabinin <aryabinin@...tuozzo.com>, Naoya Horiguchi <n-horiguchi@...jp.nec.com>, Mike Kravetz <mike.kravetz@...cle.com> Subject: [PATCH RESEND] mm/hugetlb: Don't call region_abort if region_chg fails Resending because of typo in Andrew's e-mail when first sent Changes to hugetlbfs reservation maps is a two step process. The first step is a call to region_chg to determine what needs to be changed, and prepare that change. This should be followed by a call to call to region_add to commit the change, or region_abort to abort the change. The error path in hugetlb_reserve_pages called region_abort after a failed call to region_chg. As a result, the adds_in_progress counter in the reservation map is off by 1. This is caught by a VM_BUG_ON in resv_map_release when the reservation map is freed. syzkaller fuzzer found this bug, that resulted in the following: kernel BUG at mm/hugetlb.c:742! Call Trace: hugetlbfs_evict_inode+0x7b/0xa0 fs/hugetlbfs/inode.c:493 evict+0x481/0x920 fs/inode.c:553 iput_final fs/inode.c:1515 [inline] iput+0x62b/0xa20 fs/inode.c:1542 hugetlb_file_setup+0x593/0x9f0 fs/hugetlbfs/inode.c:1306 newseg+0x422/0xd30 ipc/shm.c:575 ipcget_new ipc/util.c:285 [inline] ipcget+0x21e/0x580 ipc/util.c:639 SYSC_shmget ipc/shm.c:673 [inline] SyS_shmget+0x158/0x230 ipc/shm.c:657 entry_SYSCALL_64_fastpath+0x1f/0xc2 RIP: resv_map_release+0x265/0x330 mm/hugetlb.c:742 Reported-by: Dmitry Vyukov <dvyukov@...gle.com> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com> Acked-by: Hillf Danton <hillf.zj@...baba-inc.com> --- mm/hugetlb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index c7025c1..c65d45c 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4233,7 +4233,9 @@ int hugetlb_reserve_pages(struct inode *inode, return 0; out_err: if (!vma || vma->vm_flags & VM_MAYSHARE) - region_abort(resv_map, from, to); + /* Don't call region_abort if region_chg failed */ + if (chg >= 0) + region_abort(resv_map, from, to); if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) kref_put(&resv_map->refs, resv_map_release); return ret; -- 2.7.4
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